Medicine is the natural home of the untested hypothesis, says Hugh Pennington while wondering why doctors are so unscientific.1 When the pain started to go down my left arm, one day some four years ago, I considered my family history of heart disease and came to the obvious conclusion. So the next day I cycled from University College London to the Royal Free Hospital, up Hampstead Hill, to my relief without a twinge. With the angina hypothesis disproved, I could safely ignore the pain, which was conveniently …